Abstract: OBJECTIVE:To evaluate the molecular mechanism underlying the beneficial effect of Bushen Qiangjin capsule(补肾强筋胶囊, BSQJ), a Traditional Chinese Medicine, on knee osteoarthritis(KOA).METHODS:In the present study, 32 female Sprague-Dawley rats were randomly divided into four groups:control, KOA, high-dose BSQJ(H-BSQJ), and low-dose BSQJ(L-BSQJ). After successfully establishing the KOA model by intra-articular injection of papain, H-BSQJ and L-BSQJ groups were intragastrically administered 0.243 and 0.122 g/kg BSQJ, respectively, daily for 6 weeks. At the end of the experiment, knee articular cartilage tissues of rats were collected for evaluation by hematoxylin and eosin staining, Safranin O-Fast Green staining, and terminal deoxynucleotidyl transferase-mediated d UTP nick-end labeling assay. Serum interleukin-1βand tumor necrosis factor-α levels of rats were detected with an enzyme-linked immunosorbent assay method. Gene expression of Wnt-4, β-catenin,Frizzled-2, glycogen synthase kinase-3β(GSK-3β),cysteinyl aspartate-specific proteinases 3 and 9(caspases 3 and 9), collagen type Ⅱ alpha 1(Col2 a1), and matrix metalloproteinases 1 and 13(MMP-1 and MMP-3) of rat knee articular cartilage was quantified by reverse transcription-quantitative polymerase chain reaction analysis. Wnt-4,β-catenin, Frizzled-2, GSK-3β, cleaved caspase-3,and cleaved caspase-9 protein expression in rat knee articular cartilage was determined by western blot analysis.RESULTS:BSQJ obviously reduced pathological damage and matrix degradation of articular cartilage in KOA rats. Compared with the KOA group,H-BSQJ rats exhibited downregulated m RNA and protein expression of Wnt-4, β-catenin, Frizzled-2,and caspase-3, as well as upregulated m RNA and protein expression of GSK-3β. In addition, H-BSQJ significantly increased m RNA expression of Col2 a1 and decreased m RNA expression of MMP-1 and MMP-13.CONCLUSION:BSQJ exerted a beneficial effect on KOA by a mechanism involving downregulation of the Wnt/β-catenin pathway, which inhibited both cartilage extracellular matrix degradation and chondrocyte apoptosis to ameliorate KOA in rats.

Key words: papain, osteoarthritis, knee, Wnt signaling pathway, cartilage, Bushen Qiangjin capsule